A gunman who killed four people when he stormed a skyscraper in the heart of New York on Monday evening left a note that appeared to blame the National Football League (NFL) for his brain injury, the city's Mayor Eric Adams has said.

Four people were killed, including a police officer, and one was seriously injured when a gunman opened fire inside an office building before killing himself.

No motive has been announced. A suicide note was found expressing grievances with the NFL and saying Tamura suffered from CTE, a source said. Follow for live updates.

A note found in the gunman's wallet was critical of the NFL and mentioned CTE. The 27-year-old wrote, “Study my brain please. I’m sorry."

Four people were killed when a gunman opened fire in New York City. President Donald Trump said the U.S. would work with international partners to set up food delivery centers in Gaza. And GOP lawmakers’ efforts to outlaw “weather modification” pushes a fringe theory into the mainstream.

Authorities are responding to a call of shots fired in a Midtown Manhattan office building, police told the BBC. A BBC News editor is near the scene. She reported seeing scores of police vehicles and at least one person with a bloodied chest being taken away.

Officials warned young children and those with respiratory illnesses to take precautions. For weeks, smoke from Canadian wildfires has been drifting across the border.

By Mark Prussin Click here for updates on this story New York City (WCBS) — The New York City Police Department Animal Cruelty Squad is searching for a man who allegedly set a dog on fire after he dragged it down a street.